自定义View - 14.View绘制流程入口

wm.addView(decor,l);
-->WindowManagerImpl.addView()
-->ViewRootImpl.setView(view, wparams, panelParentView);
-->requestLayout();
-->scheduleTraversals();
--> doTraversal();
-->performTraversals();//到这里才开始View的绘制流程.